Question

By selling a watch for Rs 40 , a shopkeeper suffer a loss of 1/9 times its cost price. if he sold the watch for rs 50 . Find his gain %​

Answer 1

S.P. = Selling price , C.P. = cost price

S.P. of 40 pins = 1

S.P. of 1 pin = 1/40

Since it is at loss of 25%

Edit 1

C.P. of 1 pin = S.P. of 1 pin/0.75

= 01/(40 *0.75) = 1/30

If shopkeeper wants profit of 20% then

New S.P. of 1 pin = 1.2* C.P. of 1 pin

= 1.2 * 1/30 = 0.04

No of pins that could be sold at Rs 1

= 1 / new S.P. of 1 pin

= 1/ (0.04)

= 25

Hope it's helpful ☺️